For example, northeast trade wind days, which occurred 291 days per year 37 years ago at the Honolulu International Airport, now only occur 210 days per year.

Jessica Garza, a meteorology graduate assistant at the School of Ocean and Earth Science and Technology, Pao-Shin Chu, meteorology professor and head of the Hawaiʻi State Climate Office; Chase Norton and Thomas Schroeder analyzed 37 years of wind speed and direction, and sea level pressure data from land-based weather stations, buoys and reanalysis data.

Persistent northeast trade winds are important to the Hawaiian Islands because they affect wave height, cloud formation, and precipitation over specific areas of the region. When trades fail to develop the air can become dormant and unpleasant weather can develop.

Furthermore, Chu explained that the trades are the primary source of moisture for rain, and that a dramatic reduction could fundamentally change Hawaiʻi’s overall climate.